Hi Chris,
Easy Profile not do this natively, but you can do with 2 ways:
1. Build a simple plugin
2. Use Acymailing Filters
1. Build a simple plugin
You can use our triggers and create a plugin (based on our skeleton plugin) to do this, docs and skeleton plugin at
http://docs.easy-profile.com/index.php/article/triggers
2. Use Acymailing Filters
Acymailing allow you to filter users and make actions (for example subscribe user to list), you can use our Acymailing filter plugin to use Easy Profile custom fields*, read docs at
http://docs.easy-profile.com/index.php/article/integration-acymailing
NOTE* checkbox field type store value in a multivalue format (JSON), so for example if you have one option like
1|please send me the newsletter
then you need to set filter like: if field
equal to ["1"] add to list...
or most simple: if field
contain 1 add to list